code: def _test_subscribe(self):
      marketplace = Marketplace()
      marketplace.subscribe("marketcap")
      pass
  
file_path: catalyst/tests/marketplace/test_marketplace.py
imports: from catalyst.marketplace.marketplace import Marketplace
  from catalyst.testing.fixtures import WithLogger, CatalystTestCase
label_desc: Use image node_id 3 for calling the TestMarketplace obj's underlying member method code with example usage: obj._test_subscribe() without return types